nav {
  position: absolute;
  width: 100%;
  height: 50px;
  left: 0;
  bottom: 0;
  background: #ddd;
  display: flex;
}

nav li {
  list-style: none;
  flex: 1;
}

nav a {
  display: flex;
  width: 100%;
  height: 100%;
  justify-content: center;
  align-items: center;
}